[peteeng]

Hi Craig - Makers are an interesting bunch. We want to make stuff. Either we think we can do it for less cost or we just want to do it. It takes a machine bigger then the machine you want to build to finish the machine you want to build. This incurs cost and logistics. Especially with big machines. Many Makers do not fully cost options and go down various paths and get trapped. Many do not have access to hot casting facilities. Some on the forum make their own foundry (good on them!!) but cold casting solutions are viable but you still have to machine the parts to get to the desired precision machine. Our machine building forebears built a series of machines to get to the machine they wanted eg the first machine lathe was built by Jesse Ramsden C1775. He hand made all the parts of No1 then used No1 to make No2 etc. Each one becomes more accurate. This has been continued onward till today in industry we now have magnificently accurate machines and we are getting better. Large casting will be replaced by 3D printing in my lifetime. Megacasting probably will be good for some time yet.... I think all us Makers go down various rabbit holes and depending on our experiences, resources and objectives come out at different destinations. The 1000s of threads here are testimony to that!! Keep Making Peter

[ardenum]

Hey Peter,

I've been thinking on how to additionally stabilize the rails on the surface plate. Came up with a vice style micro clamp for each bolt, from each side. I'm wondering if it's more trouble than it's worth. I'm trying to not do any cutouts in the plate and only drill holes to put inserts in. How would you go about analyzing something like this? any gut feelings? pictures attached

By the way, I did that previous FE and it seems that for my particular application (hole spacing 60mm apart) the biggest insert would be D25mm and anything bigger affects the granite.

[peteeng]

Hi Ard - There are commercial systems like that. The bearing manufacturers probably have something so talk to them. Peter

[joeavaerage]

Hi,

You mean casting in iron/steel? you have a contact to some cheap chinese forge maybe?

No, I have a foundry about 500m, in a straight line, from my place of work. Their single pour iron capacity is only 65kg, however for my pours (100 kg plus) they send it to Timaru, a large town
approx 2hrs drive away. The foundry there can pour 1.5 tonnes. So my local foundry become my pattern makers, they have a tame pattern maker they call in as required,
and my mold makers. The head man has been a foundryman his entire working career, 40 plus years. His knowledge and experience is invaluable.

The heat treating business is about 500m in the other direction, and the large format CNC engineering company is about 1000m south from here.

This quote from Peter is particularly apt:

Many Makers do not fully cost options and go down various paths and get trapped.

In some respects I did this to myself, getting iron cast, heat-treated and machined is an eye-wateringly expensive business, but the results are superb.
Some months/years after I've paid the money I come to realise that the results I've got are actually very good and compare favorably or better
than coldcasting, on the basis of available evidence.

Ard's last post is a classic example. He has come up with a masterly design to hold the linear guides perfectly straight, but at significant complexity.
If however you were mounting rails on cast iron you just drill the straight line of holes, tap, and screw the rails down. If you demand extra certainty
of linearity then abut the rail to a linear edge machined into the casting. Easy.

What bemuses me, and is the true basis of my posts is that many Makers go down the path of coldcasting as a means to avoid heat treatment and machining
and in so doing force upon themselves costs and compromises that result in a lesser machine.

Craig

[peteeng]

Hi Craig - You live in a particularly beautiful part of the world. The green around there hurts your eyes NZ is also great because its manufacturing capability is still at a reasonable/advanced level. You can get most things done even make low orbit rockets. Peter

[ardenum]

Ard's last post is a classic example. He has come up with a masterly design to hold the linear guides perfectly straight, but at significant complexity. If however you were mounting rails on cast iron you just drill the straight line of holes, tap, and screw the rails down. If you demand extra certainty of linearity then abut the rail to a linear edge machined into the casting. Easy.

We're all limited by our budgets Craig and even if I wasn't I'm not sure I wanna pay more then 5k for any type of a machine and I have big requirements mind you. Doing the thing properly, either cold or hot casting, aging, heat treating, I know if I do that, it will work but where's the fun in that?

What started as a project to just machine parts transformed into something else. An endless source of interesting challenges that keep your mind occupied for days on. I don't even care about making those previous projects anymore. This is THE project and it just keeps on giving!

Figuring out how to achieve a similar result for half the price and the thrill of doing something that no one did before. The journey doing this is my greatest pleasure... and my mission:

...to explore strange new worlds. To seek out new life and new civilizations. To boldly go where no man has gone before!

[pippin88]

Hey Peter,

I've been thinking on how to additionally stabilize the rails on the surface plate. Came up with a vice style micro clamp for each bolt, from each side. I'm wondering if it's more trouble than it's worth. I'm trying to not do any cutouts in the plate and only drill holes to put inserts in. How would you go about analyzing something like this? any gut feelings? pictures attached

By the way, I did that previous FE and it seems that for my particular application (hole spacing 60mm apart) the biggest insert would be D25mm and anything bigger affects the granite.

Your proposal also allows you to dial in / adjust the straightness of the rail (side to side).

I've seen a few other ways used to do this:

Dowel pressed onto the side of the rail by a countersunk head screw

Horizontal cam (John McNamara https://www.model-engineer.co.uk/for...?th=139042&p=1)

[peteeng]

Hi Pippin - Johns builds and documentation are amazing... There's quite a lot of info on mounting the linear guides in manufacturers manuals. See the Hiwin its typical of the info available. Peter

as an aside here's a very happy young whale. In Britain, NZ and Oz we say I'm as "happy as Larry" so the whale must be Larry. Apparently Larry was a famous OZ boxer who didn't loose a bout and di quite well out of the prize money....

[ardenum]

Hey Pete,

Ever had a customer request biocompatible materials in one of your boat jobs? Things like non-toxic plastics and adhesives with very low outgassing specs?

Thinking of building a sleeping pod and using stuff like hdpe, pp, nylon etc. but at a loss when it comes to bio adhesives...these things are known to be hard to glue...

[peteeng]

Hi Ard - Low energy surface materials can be a challenge but the auto industry does it all the time these days. Surface primers are available for PP etc for painting. These are the same for bonding. The auto industry has a range of adhesives for metals, plastics etc. Talk to your local spray painter/panel beater supplier they will have answers. If they are non toxic low outgassing etc thats another question. 3M have a line called scotchweld I have used these for HDPE and they certainly worked. Plus look up corona surface prep or flame prep that makes a huge difference. That's now std practice in aero and auto for ambient temp assembly. Peter

https://youtu.be/P7fi4hP_y80

[ardenum]

Hi Ard - Low energy surface materials can be a challenge but the auto industry does it all the time these days. Surface primers are available for PP etc for painting. These are the same for bonding. The auto industry has a range of adhesives for metals, plastics etc. Talk to your local spray painter/panel beater supplier they will have answers. If they are non toxic low outgassing etc thats another question. 3M have a line called scotchweld I have used these for HDPE and they certainly worked. Plus look up corona surface prep or flame prep that makes a huge difference. That's now std practice in aero and auto for ambient temp assembly. Peter

Thanks

[peteeng]

Hi Ard- in the video the flame prep may look sophisticated but I use a propane torch wafted over the surface. This removes moisture and contaminates the surface with flame residue (they prefer to say activates the surface). This increases the surface energy. Its a fast waft with no visible damage to the surface!! We are not burning the surface!! Peter

[peteeng]

Hi All - Back to spindles. I was at the machinist who has been doing parts for me for over 10 years ( I was making scooter wheels for him over 11 years ago) and started talking about feeds and speeds etc. Usually his busy so can't talk.... but the job he had on his big Mazak was roughing at 280metres/min 10mm tool 4F 5mm deep and 1mm radial in steel. I was seriously impressed. He uses Guhring tools. He said 6000rpm not fast enough for HSM so maybe the ER20 Gpenny metal is good to go. I'd better get out and about more often....Peter

[HXX-Leon]

We produce DRO and linear scale, maybe it will help you, you can go to https://www.amazon.com/stores/HHXXOV...2?ref_=ast_bln
view on
Or on Whats: +8613528773691
Contact me at [email protected], [email protected]

[peteeng]

Evening All & Sundry - I have started thinking about Milli again. A machine has to have a reason to exist. A raison detre. Milli's would exist because none of the machinists I use will machine glass fibre or carbon fibre laminates on their machines. So Milli would be a composite specific machine (nearly). I will have a requirement to machine composite gantries so I will need a long machine say about 1500mm long but only 300-400mm wide. So a gantry machine will have a very big footprint to achieve this. So I keep coming back to a moving column machine like the Mori attached. I want the "table" drive to be out of the muck especially composite sludge so a fixed table is the go. The base and saddle can be cast grout with bonded on aluminium subplates for the precision machined areas. My big concern is aligning all of these pieces. Still have not found an economical geometric alignment system for this grade of machine. I don't have a spare $30,000AUD for a laser system that can align to 0.001mm

Concepts to consider are: 1) self assembly this means it will be accurate when assembled. This means all parts are accurately machined on high quality mills. This means using aluminium or steel for all parts.... 2) or making composite bulk parts with metal inserts then finish machine the inserts. This will work and be more economical then full billet machining parts 3) The only composite that I have made that equals aluminums stiffness is carbon fibre and it will be very pricey compared to bulk aluminium 4) I maybe able to machine fibre composites dry or nearly dry. I have trialed diamond tooling on my router and so far so good.... 5) I have settled on a 1.5kW ER20 spindle but these are all air cooled spindles. The ER20 2.2kW is water cooled but big for a Maker size machine. ER20 means a 1/2" bit can be used whereas an ER16 is Dia10mm max 6) I have recently started using Fusion360 and am struggling with the learning but it seems Milli will be a good learning project going fwd 7) So I want to make the smallest machine as a starter machine based on the 1.5kW spindle and work outward from there.... I'll speak to G-Penny and try to get the bearings upgraded... Lets see how all that logic goes.... Peter

[ardenum]

Hi All - Back to spindles. I was at the machinist who has been doing parts for me for over 10 years ( I was making scooter wheels for him over 11 years ago) and started talking about feeds and speeds etc. Usually his busy so can't talk.... but the job he had on his big Mazak was roughing at 280metres/min 10mm tool 4F 5mm deep and 1mm radial in steel. I was seriously impressed. He uses Guhring tools. He said 6000rpm not fast enough for HSM so maybe the ER20 Gpenny metal is good to go. I'd better get out and about more often....Peter

HSM is usually 12000 RPM and your DOC and torque determine how much of the flute length you can engage. Otherwise the other option is datron style/dental milling. You thinking of the 3.7kW metal version? I'm thinking getting the same...

A traveling column is very appealing, like you said you want to start small, which is perfect because you can do a small bed first and then you can elongate it and reuse the whole column assembly. If you wanted to machine metals then a DMF200/8 would be better because the stiffness would be the same wherever the spindle is, the machine you mentioned has different stiffness depending on how much the spindle box is extended but for composites I'd think it's negligible. For a small machine you also only need a precision triangle/square for alignment.

[peteeng]

Hi Ard - Yes the DMF 200 is probably better in the constant stiffness dept. Thanks for that. There were several Milli versions similar. The hiccup is the base stiffness / weight ratio in all of these designs. I have tended to be on the light side for the bae. Would have same footprint as M1.... 3.7kW is a bit big for Maker grade machines. It really only needs a 800-1kW spindle but can't get that size in ER16 or ER20. I think the 1.5kW ER16 is close to the sweet spot. But would be good to be able to use bigger then 10mm occasionally. Maybe need to make an ER20 adaptor. But I have an ER16 1.5kW on order and will play with that on a customers machine to get a feel for it. Will use ER11 collets as tool holders maybe. Back to my Fusion tutorials... Peter

Re alignment - my current thoughts are to get my machinist to make some bespoke squares and guides

[peteeng]

Hi Ard - I want the drives way above the muck so I think after contemplation the M1 is better for that. Cheers Peter

[ardenum]

Hi Ard - I want the drives way above the muck so I think after contemplation the M1 is better for that. Cheers Peter

I'm with you on that. QoL is definitely something that is lacking in diy machines and with the M1 you also have a very clean way cover assembly that's very straightforward to implement. You basically only need 2 covers for left and right.

[peteeng]

Evening all - I've been wondering about bolted joint stiffness for various parts of Milli. So I dummied up a Z axis assembly. made from 16mm thick aluminium plate. 500mm long and 200mm wide. The spindle would bolt inside it. I placed 100kgf on the bottom edge and did up the M6 bolts to 0.7x UTS ie 26x0.7=18.2kN preload. I used 0.3 as the friction co-efficient for the contact. I ran the model and determined that the connection did not gap so came back until I got to 14kN at which I could just see some slippage. 14kN is the nominal pretension for a 12.9 class M6 bolt. So in this condition the bolted assembly deflects 0.127mm and the bonded version deflects 0.109mm this is an efficiency of 85%. I could use bigger bolts say 10mm or even 12mm to see how that goes. M6 is too small I think into16mm plate. I may rebuild at M10.... but 85% gives me a general figure... Peter

M10 has nearly 3x the area of a M6 screw so is much stiffer...

edit - running M10 bolts (cl;ass 12.9) at same tension raised the efficiency to 90% M10 capscrews can be torqued at 40kN vs 14kN but at this torque not much difference in deflection.